The purpose of this project is to develop methods for gene transfer to mammalian cells and to use these techniques for gene mapping, analysis of gene expression, and cloning eukaryotic genes. Many independent somatic cell hybrid lines segrating human chromosomes have been isolated and the human chromosome content of each line determined. Analysis of these lines with isotopically labeled cloned DNA probes has allowed assignment to specific human chromosomes, and sometimes regional localization, of human cellular onc genes including N-ras, c-myb, c-kis-1, c-kis-2, c-mos, c-myc, c-bas-1, and c-sis. Many of these c-onc genes map to the same sites as non-random chromosome rearrangements in specific human cancers. Similar procedures were used to map Alpha, Beta, and Gamma fibrinogen genes to human chromosome 4; chromosomal mapping of a multigene metallothionein family and aryl hydrocarbon hydroxylase gene are in progress. The human thymidine kinase gene has been molecularly cloned and fragments subcloned for analysis of its structure and regulation.